34 



I.ECTUKE III. 



use. These appendages are longer than the body in some species, as 

 the Notommata Tigris : tlieir sheath is much elongated and slightly 

 annulated in the Brac/doni : it is telescopiform in Scaridium : both 

 claspers and sheath are wanting only in the Amirceus. The integument 

 of the body is smooth, and never ciliated : although the parasitic jointed 

 fibres of Hygrocrocis, which attach themselves sometimes to the in- 

 tegument of the larger species, as Notommata centrtira, give it that ap- 

 pearance. The PolyarthrcB have long jointed filaments, like the rays 

 of a fish's fin, attached to the sides of the body. 



Not any of the species are known to secrete a silicious shell ; but 

 many of them are provided with a transparent gelatinous case, into 

 which they can contract their bodies ; thus offering another analogy 

 to the Ciliobrachiate Polypes, and also to the bivalve-sheathed Ento- 

 mostraca. The loricate genera are Noteus, Anurcea, Brachionus, and 

 Pterodina. In all the species the shell is a cylinder or case {testida^, 

 not a mere shield (^scutelluni). 



Horn-like processes project from the front margin of the shell in 

 some species of Brachionus, and from both front and back margins in 

 other species. In some Notei and AnurcecB the shell is ornamented 

 by large pentagonal or hexagonal groups of granules. 



The cephalic cilia are aggregated into from two to five groups, upon 

 lobes (Jig. 15, a), which sometimes are developed into short tentacular 

 processes, with a verticillate arrangement of cilia, as in Step/ianoceros. 

 These lobes or processes Ehrenberg regards as muscular. The 



movements of the ciliated quasi- 

 wheels are under the control of 

 the will. They can be instantly 

 arrested, the whole apparatus 

 drawn out of sight, again pro- 

 truded, and as instantly set in 

 motion. The muscles which pro- 

 trude and retract of the ciliated 

 lobes, which bend and modify the 

 form of the body, and which 

 throw out, attach, or heave in the 

 anal anchors, are developed in 

 the form of distinct fibrous fas- 

 ciculi. You perceive in this dia- 

 gram, for example (fig. 15.), the 

 Notommata. retractors of the oral cilia and of 



the anal forceps ; the iong and narrow longitudinal muscles (b, b), 

 which shorten the whole body ; and their antagonists the transverse 



